The present invention relates to a tunneling system, notably for mine galleries or roads.
The digging of subterranean galleries implies three distinct operations which, conventionally, are carried out successively, namely working or cutting, removal of the dug earth and support.
Cutting has been mechanised by the use of cutting tools mounted on a chain or on a drum and associated with a frame advanceable continuously. It is also known to mechanise the removal of dug earth by mechanical scraper arms which draw them towards a conveyor belt.
However, it is still necessary to stop this continuous advance of the working face, mine face or mine head, to proceed with the installation of supporting means under the portion of the roof which has just been formed.
On the other hand, the stability of the whole against the reaction forces which are exerted on the cutting tool is essentially ensured by the weight of the frame. Now this frame is generally of moderate height and the tool is articulated to it at a relatively low point, so that the reaction forces tend to rock the unit. Without giving considerable weight to the frame, which is moreover prejudicial and expensive, the stability of the unit is hence precarious, and notably necessitates a limitation in the installed power. In addition, only a slight clearance between the floor and the machine exists so that it is difficult to introduce therein an independent cuttings removal member. This member is then incorporated in the machine and prevents any access to the mine face.
It is an object of the present invention to provide a tunneling system which enables the support of the roof without interruption of the cutting operation, which offers complete stability, which enables the installed power for the cutting to be notably increased, and which offers a wide clearance above the floor to install conveniently an independent dug earth removal member, enabling easy access to the mine face.
According to the invention, a tunneling system for digging subterranean galleries comprises a cutting tool articulated to a frame, and mounted so as to be movable along the height of the mine face. This frame is provided with ground support means and with propulsion means to follow the advance of the cutting, and the system is characterised in that the articulation point of the cutting tool is situated in the upper half of the system in operating position.
This position enables a very considerable free space to be preserved beneath the machine. As a result moreover, there is a cutting tool path such that the mine face has a slope closer to that of the natural slope, which reduces the risks of cave-ins or rock-falls.
According to an additional feature of the invention, the articulation point of the cutting tool is situated on a member movable with respect to the frame and capable of being moved in a direction substantially parallel to the direction of advance.
The cutting phase proper, corresponding to the path of the tool, is preceded by a phase of advance of the tool into the mine face. Due to the aforesaid arrangement, this advance is carried out not by an advance of the frame, but by the movable member, the frame remaining solidly supported on the floor and on the roof. Stability is thus better assured during this phase.
According to another feature of the invention, the shaft bearing the cutting tool is mounted on two bearings of which one is movable vertically to give the tool an oblique track in a pre-determined direction.
When, in a sloping stratified deposit, a tunnel is dug in a direction substantially perpendicular to the line of greatest slope of the layers, it is advantageous, to reduce the risks of cave-ins or rock-falls, to give the roof of the tunnel a cant corresponding to the slope of the layers. The aforesaid feature enables this cant to be formed.
According to an advantageous feature of the invention, the frame is provided with at least one support device movable on the roof of the tunnel enabling the advance of the frame in the course of the digging operation.
This arrangement has the double advantage of forming beneath the roof of the tunnel a support advancing with the whole of the system in proportion with the cutting, and, in cooperation with the floor support means, to produce a true embedding of the system in the tunnel, preserving it from any tilting.
Preferably, each roof support device is articulated to the frame through two substantially rectangular axes of rotation, so as to accomodate alignment faults of the roof.
To ensure the support, each roof support device is advantageously connected to a jack.
According to a first embodiment of the invention, each roof support device comprises a caterpillar track which is supported against the roof.
Each caterpillar track comprises at least one caterpillar cooperating with a guide path connected to a member through a double articulation with two swing axes, substantially rectangular, enabling inequalities in the surface of the roof to be taken up.
Similarly, the floor support means comprise two caterpillar tracks arranged laterally.
In this embodiment, the propulsion means comprise a drive member with linear movement of which a fixed part is connected to the frame, and of which a movable part cooperates with a rack formed in the floor support caterpillar, the path of this member corresponding to a step in the advance of the cutting tool.
In the same way as the roof support caterpillar tracks, the floor support caterpillar tracks each comprise, preferably, at least one caterpillar cooperating with a guide path connected to the frame through a double articulation with two substantially rectangular swing axes, to take up uneveness in the floor.
According to a preferred embodiment of the invention, one of the floor support caterpillar tracks is connected to the frame through a substantially horizontal articulation axis and perpendicular to the direction of advance.
This degree of freedom enables the application of the two caterpillars to the floor to be ensured, even in the case of a fault in the general flatness of the latter.
According to a further improved feature of the invention, the frame comprises a flat cross piece located at the level of the floor support caterpillar track and provided with liftable inclined planes to facilitate the crossing thereof.
The system is thus provided with an upper cross-piece and a lower cross-piece, which improves its rigidity. On the other hand, the embodiment indicated introduces no impediment to access to the mine face or to the passage of dug earth removal mechanisms.
According to a second embodiment of the invention; the roof support device comprises at least one sliding member articulated to the frame and provided with shoes to cooperate with the beams held applied to the roof by said member.
These beams play the role of slide path for the frame and ensure at the same time the support of the roof immediately behind the mine face.
The sliding member then comprises advantageously retractable feet to take support on the roof and disengage the beams in order to advance them on each advance step of the digging.
Similarly, the frame comprises slide shoes to cooperate with the support beams placed laterally on the floor.
In this embodiment, the advance means comprise a drive member with linear movement of which a fixed part is connected to the frame, and of which a movable part is connected to a support-beam.
In the same way as for the roof beam, the frame comprises retractable feet to become supported on the floor and disengage the support beams, to advance them on each step of advance of the digging.
In the case of digging a tunnel with curvilinear cross-section, the invention provides for the roof support devices to be arranged obliquely to take support on the roof of such a tunnel.
The cutting tool then comprises a truncated cone furnished with tools mounted at the end of a shaft connected to the chassis through an articulation enabling angular movement of the arm in two substantially perpendicular planes.
The composition of these two movements enables the curvilinear movements to be realised corresponding to the profile of the tunnel.
Preferably, the articulation of the arm of the frame is mounted slidably on a substantially horizontal cross-member of the frame.
It is thus possible to utilise a relatively short arm, such that the path of the tool has an accentuated curve, and compensates for the curvature which results therefrom on the mine face through operations led successively by placing the articulation of the arm at different points of the cross piece.
Other features and advantages of the invention will emerge also from the detailed description which follows; this relates to preferred embodiments of the invention given with reference to the accompanying drawings, purely by way of non-limiting examples.